Rationale: Transplantation Medicine requires, arguably, the most complex set of molecular tests in all of laboratory medicine. The astounding diversity of the Human Leukocyte Antigen (HLA) gene locus is well known and has given rise to complex DNA-based HLA allelotyping as the core technology for all Tissue-Typing. The companion immunodiagnostics branch of Transplantation Medicine is even more intricate and is being used to detect antibodies against the HLA proteins themselves as a way to predict hyperacute graft rejection at the time of transplantation or over time, post-transplant changes in donor-specific anti-HLA antibody levels, which is the determining indicator of the earliest stages of graft rejection. Any useful anti-HLA antibody detection test must be capable of detecting one or more of nearly 300 possible serum-borne neutralizing antibodies, each with a Class I or Class II HLA protein as its cognate antigen. The world-wide market for anti-HLA serology is in excess of $300 million with a growth rate of 11%/yr and is dominated by a single test provider (Thermo-One Lambda) that sells a Luminex bead-based anti-HLA antibody test featuring beads coated with membrane protein extracts. In spite of their seminal market position, Key Opinion Leaders in the transplantation marketplace feel that the expensive Thermo-One Lambda test has poor sensitivity, specificity and reproducibility. To solve the crucial Transplantation Testing problem in a way that will rapidly build market share, the core of this Phase II plan is to expand the ongoing partnership and commercial collaboration between Pure Protein LLC (PP); a company that has invented and holds intellectual property for a novel way to produce stable recombinant soluble HLA (sHLA) complexes in eukaryotic suspension cultures and GMSbiotech (GMS) a company that has developed and patented a unique approach to link large sets of metastable proteins like HLA, while retaining fully-native protein folding, onto test surfaces in a microarray format. Preliminary studies by PP & GMS show extensive data demonstrating that the sHLA proteins (Class I & Class II) manufactured by PP can be fabricated into a low cost microarray test using the GMS technology suite. The goal of this proposal is to complete design and fabrication of two microarray tests: (1) EZScreenTM I, representing a set of 120 Class I recombinant sHLA protein probes and (2) EZScreenTM II, representing a set of 110 Class II recombinant sHLA probes. Upon completion of this Phase II, both kits will be ready for RUO product launch and the beginning of FDA review.